var db = require('../../common/db')
var auth = require('../../common/auth')
var log = require('../../common/log')
var RESPONSE = require('../../common/response').RESPONSE
var ERROR_CODES = require('../../common/response').ERROR_CODES

exports.main_handler = async function (event) {
  try {
    var method = event.httpMethod || 'GET'
    var path = event.path || ''
    var body = parseBody(event)

    if (method === 'POST' && path === '/api/v1/auth/login') {
      return await wxLogin(body, event)
    }

    if (method === 'POST' && path === '/api/v1/auth/refresh') {
      return await refreshToken(body)
    }

    return RESPONSE.error(ERROR_CODES.PARAM_ERROR.code, 'unknown route')
  } catch (err) {
    console.error('auth error:', err)
    return RESPONSE.error(ERROR_CODES.SERVER_ERROR.code, err.message)
  }
}

async function wxLogin(body, event) {
  if (!body.code) {
    return RESPONSE.error(ERROR_CODES.PARAM_ERROR.code, 'missing code')
  }

  var wxResult = await requestWxSession(body.code)
  if (!wxResult || !wxResult.openid) {
    return RESPONSE.error(ERROR_CODES.INVALID_TOKEN.code, 'wechat login failed')
  }

  var users = await db.query(
    'SELECT id, openid, nickname, avatar_url, phone, status FROM users WHERE openid = ? AND deleted_at IS NULL LIMIT 1',
    [wxResult.openid]
  )

  var userId
  var isNew = false
  if (users.length === 0) {
    var result = await db.insert(
      'INSERT INTO users (openid, nickname, avatar_url, status) VALUES (?, ?, ?, 1)',
      [wxResult.openid, body.nickname || null, body.avatar_url || null]
    )
    userId = result.insertId
    isNew = true
  } else {
    userId = users[0].id
    if (body.nickname || body.avatar_url) {
      await db.update(
        'UPDATE users SET nickname = COALESCE(?, nickname), avatar_url = COALESCE(?, avatar_url) WHERE id = ?',
        [body.nickname || null, body.avatar_url || null, userId]
      )
    }
  }

  var token = auth.generateToken(userId, wxResult.openid)

  await log.writeLog({
    operator_type: 2,
    operator_id: userId,
    target_type: 'user',
    target_id: String(userId),
    action: isNew ? 'create' : 'login',
    ip_address: getClientIp(event)
  })

  return RESPONSE.success({
    token: token,
    user_id: String(userId),
    user_info: {
      id: userId,
      nickname: body.nickname || null,
      avatar_url: body.avatar_url || null
    },
    expires_in: 604800
  })
}

async function refreshToken(body) {
  if (!body.refresh_token) {
    return RESPONSE.error(ERROR_CODES.PARAM_ERROR.code, 'missing refresh_token')
  }

  var decoded = auth.verifyToken(body.refresh_token)
  if (!decoded || decoded.type === 'admin') {
    return RESPONSE.error(ERROR_CODES.TOKEN_EXPIRED.code, 'invalid refresh_token')
  }

  var token = auth.generateToken(decoded.user_id, decoded.openid)
  return RESPONSE.success({
    token: token,
    expires_in: 604800
  })
}

async function requestWxSession(code) {
  var appId = process.env.WX_APPID || ''
  var appSecret = process.env.WX_APP_SECRET || ''
  var url = 'https://api.weixin.qq.com/sns/jscode2session?appid=' + appId +
    '&secret=' + appSecret +
    '&js_code=' + code +
    '&grant_type=authorization_code'

  var https = require('https')
  return new Promise(function (resolve) {
    https.get(url, function (res) {
      var data = ''
      res.on('data', function (chunk) { data += chunk })
      res.on('end', function () {
        try {
          resolve(JSON.parse(data))
        } catch (e) {
          resolve(null)
        }
      })
    }).on('error', function () { resolve(null) })
  })
}

function parseBody(event) {
  if (event.body) {
    try { return JSON.parse(event.body) } catch (e) { return {} }
  }
  return event.queryStringParameters || {}
}

function getClientIp(event) {
  var headers = event.headers || {}
  return headers['x-forwarded-for'] || headers['X-Forwarded-For'] || headers['x-real-ip'] || ''
}